untraceble power problem

[pyrie]

Hi,

a year ago I bought my BMW 730i (e32), but a few months ago he started having problems with his power.

When I hit the throttle, the car accelerates, but very slow (like he is holding me back).
A few months ago, when I started noticing it, he had the problem only occasionally, but now, he never has a 'good' moment.

The strange thing is: when the power was 'holding back', the cruise control didn't work, and when the cruise control did work, the power was there.

Some things my car does which may or may not have something to do with it:
- when the engine is almost at his temperature ---) when I rev the engine, it will die when the RPM drops
- sometimes the engine is 'searching' for the right RPM (it goes up and down between 800 and 1500 RPM)
- once and a wile, when I'm at a stop sign, the speed dial goes all the way up, and back.

All the filters and oil have been replaced recently.

Anyone an idea where this problem can come from?

The garage has already 'read' the computer, but found nothing...


Really hope someone can help me!

Thx

Pieter

[shogun]

Hi Peter,
you mention the cruise control. Did you check already if that is correctly installed? Often the clips are missing, throttle safety clips BMW part no. 35401165393 , Prevents throttle cables from detaching, which can cause dangerous unintended acceleration.
http://www.nmia.com/~dgnrg/tc2.jpg
A cheap repair is shown here https://www.bimmerforums.com/forum/s...epair-for-1-72
I assume the car is with an M30 engine. With EML or normal throttle cables? EML has a motor on the throttle valve, there the idle etc is controlled by the EML control module.

Also check both fusible links for haircracks http://www.bimmerboard.com/forums/posts/377728/

[pyrie]

Hi Shogun,


I assume the cruise control is installed correctly, because it did work once and awhile. I will check this weekend to be sure.

It is indeed an M30 engine with EML
You say the idle is controlled by the motor on the throttle valve, could it be the same motor that is the cause of the lack of power.
Maybe a new throttle valve can fix the whole problem?

Or should I be looking for some broken sensors. maybe the ASC is telling the car its slipping, and thereby holding me back for safety.

Thx for your reply
Pieter

[shogun]

It might be the throttle valve, usually on our M70 engine with EML we clean it, sometimes even the carbon brushes of the motor are stuck. A new throttle valve is extremely expensive, that is why we all clean them and they work again
DK motor clean up, this is from the M70, but basically the same for the M30 http://www.mwrench.com/Whitepapers/DKMotorcleanup.pdf
Testing data are on my website below under reference data>>throttle body input details.
The EML controls it all, also the throttle position, see here http://www.europeantransmissions.com...MW/EML-BMW.pdf
Understand German language? Then click here, here is my collection of pics, data and specs for EML problems http://www.7-forum.com/forum/24/dros...-e32-5321.html

Is the EML light coming on when you switch ignition on and then it disappears? If not, or not at all, then you have to fix that first, because without working EML light is always limpmode
see here http://www.7-forum.com/forum/24/eml-...ten-41084.html

[pyrie]

Hi,
thanks for all this good information!!
I just spend some hours working on my car and especially looking the internet.
I'm done cleaning the throttle valve, the carbon brushes where in good condition, but I cleaned the whole thing just to be sure. (wasn't as bad as the pictures you put on this forum earlier

My EML light never works,you said when the EML light doesn't work, the car will always drive in limpmode, so if I get this correct: fixing this 'simple' light could be the key of this whole problem?

Is this: http://bmwe32.masscom.net/johan/eml_bulb/eml_bulb.html
the only way to fix this light, or is there a more simple solution?

I already changed some light bulbs for the 'check engine', 'seat belt' and ASC, but if I get this right, the EML light is on the PCB itself?

Another thing: like I said, I already changed the ASC light, but it doesn't work, is it possible it will only work when the EML light is also fixed?

Gr.
Pieter

[SergeBMW]

Its the simplest of fixes. The light is soldered directly to the PCB, the wire bypasses the faulted section. It takes about 10 minutes or less tbh.
Before anything check for continuity on the bulbs. Make sure to sand off the coating on the pins as you wont get a reading with it left on.

[pyrie]

woehoe,
guys, this is amazing!!!!!
indeed, 10min work (for a friend who nows what a PCB is )

Power was back for a short run, afterwards the EML light came on, and the power was gone, but later on it was fine.
So maybe it was just a short error, we will see.

Anyway, the cruise control works fine, the idle is more stable, and even the fuel consumption has dropped from 14.5L/100km to 12L/100km.

So it looks all my problems are fixed because of your help.
A simple fix, but hard to find in the 'non digital' world.

THX !!
Pieter

[pyrie]

Damn,...

I hoped the EML problem was fixed, but once and awhile the light turns back on and the car goes back in limpmode.

I already did the ASC blink test, but no problem there.

Is there an other way to find problems with the EML, or is this the point where I have to go to a dealer and let his computer do the work?

[pyrie]

When I hit the throttle aggressively, I feel the engine shake, could that be an broken engine support, or is it just me not used to the extra power.

I also noticed the EML light never comes on when the engine is cold or warm, always when the temperature is somewhere in between.

[shogun]

How do the engine mounts look? Oil on the outside? Cracked? They are filled with oil http://www.nmia.com/~dgnrg/page_10.htm

Ever cleaned the throttle valve? Especially where the motor is, there are 2 carbon pieces which could get stuck sometimes, see here, that is from M70, but should be similar http://www.mwrench.com/Whitepapers/DKMotorcleanup.pdf
Checked the coolant temperature sensor, data here in German language http://www.e32-schrauber.de/bmw/s-tempsensor.htm

E32 Bentley Repair Manual page 130-45.
EML Pedal Position Sensor Test
pedal at idle poisition
manual transmission 0.34-0.43 VDC
automatic transmission 0.35-0.45 VDC

pedal at full throttle
manual transmission 3.1-3.3 VDC
automatic transmission 3.7-3.8 VDC

EML connector pedal position test pin
M70 DME 1.2 brown/violet pin 1
M70 DME 1.7 blue/brown pin 20
M30 DME 1.3 blue/brown pin 20

terminal numbers are molded in the EML connector face. These numbers are very small and may be difficult to read.

set a gap of 3mm between accelerator pedal bracket and the idle stop
To check adjustment, peel back rubber boot from EML harness connector (round big plug in engine bay left side close to the heater valves) and connect digital voltmeter between specified pin in connector and ground.

[pyrie]

I've tested the engine mounts, and they are OK,
Throttle valve is clean now, and was in much better condition than yours
And tested the coolant temperature sensor at about 70°C witch showed the correct ohms.

Now: once and awhile the OBC says: 'coolant level' but the reservoir is full.

Is there a float in the reservoir, and could it be the float is rusted so it makes a bad contact?

I have the feeling the EML error has something to do with the 'coolant level' warning.

[shogun]

The coolant level sensor is a very simple unit and is located on top of the expansion tank, usually the float soaks water when old and then it does not go up. https://www.ecstuning.com/b-genuine-...r/61311378320/
or rhe connector is broken and has no contact, you can test that by using a small wire bridge and bridge the 2 wires.
plug housing 61131378408 2-pin https://www.ecstuning.com/b-genuine-...61131378408kt/

[pyrie]

When I bridge the two wires, the 'coolant level' warning is gone so that's a good thing. just gonna replace the sensor and connectors (they broke).

Strange thing: with the bridge, the EML light immediately comes on, and doesn't go out. Does the OBC knows I'm trying to fool him???

[pyrie]

Well,
I replaced the coolant sensor in the expansion tank.
The warning 'coolant level' is gone, but the EML warning keeps coming back.

It only comes when the engine is almost at temperature, when the EML is on, I simply kill the engine, start again, and the warning is gone.

Now, I tested the 3 NTC sensors (blue, beige, black)
the blue and beige gave the same result (300 Ohm when the car was almost hot)
The black sensor gave 600 Ohm.

Are those 3 sensors the same type, or is the black one a different one?

[shogun]

it is all in the workshop manual under specifications, engine electrical
for example https://www.bmwtechinfo.com/repair/m...ges/941295.jpg
https://www.bmwtechinfo.com/repair/main/941en/index.htm
find out the part numbers with your VIN on realoem of the sensors and then google with these numbers, often online vendors have the cpl. specs

probably
ENGINE COOLANT TEMP SENSOR 2-POL 12621710535
Temperature sensor, water 13621709967
Temperature sensor, water M14X1,5 12621288158

I found for example
Hersteller: HELLA OE 13621709967: Kühlmitteltemperatur-Sensor NTC-Sensor blau geschraubt mit Dichtung
Widerstand [Ohm]:2080, Temperaturbereich [°C]:25 ,Nennspannung [V]:12, Sensorart:NTC-Sensor, Farbe:blau, Gewindemaß:M12x1,5
-------------------------
BOSCH Temperature Sensor (20 deg. C, 2500 Ohm.) (White Top) 12621288158
------------------------------------------
12621710535 black
Kurzbeschreibung: Temperaturbereich bis: 130 °C, Länge: 53 mm, Außengewinde: M14 x 1,5 mm, Schlüsselweite: 19, Anschlussanzahl: 2, Farbe: schwarz, Schraubenlänge unter Kopf: 27 mm

Coolant Temperature Sensor,Number of Poles: 2, Temperature Range: 25 °C, Resistance: 5000 Ohm
http://spareautoparts.eu/autoparts/s...621710535/BMW/

[pyrie]

Thanks Shogun!!

Think I'm getting closer, all the temperature problems are solved (I hope).

I went to the dealer this week to do a computer readout. Result: 1 fault:
'throttle valve potentiometer'

Is that a part of the DK motor (carbon brushes?), or is that the same of the accelerator pedal potentiometer?